// Copyright 2006 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.


// Known Issues:
//
// * Patterns only support repeat.
// * Radial gradient are not implemented. The VML version of these look very
//	different from the canvas one.
// * Clipping paths are not implemented.
// * Coordsize. The width and height attribute have higher priority than the
//	width and height style values which isn't correct.
// * Painting mode isn't implemented.
// * Canvas width/height should is using content-box by default. IE in
//	Quirks mode will draw the canvas using border-box. Either change your
//	doctype to HTML5
//	(http://www.whatwg.org/specs/web-apps/current-work/#the-doctype)
//	or use Box Sizing Behavior from WebFX
//	(http://webfx.eae.net/dhtml/boxsizing/boxsizing.html)
// * Non uniform scaling does not correctly scale strokes.
// * Filling very large shapes (above 5000 points) is buggy.
// * Optimize. There is always room for speed improvements.

// Only add this code if we do not already have a canvas implementation
if (!document.createElement('canvas').getContext) {

(function() {

  // alias some functions to make (compiled) code shorter
  var m = Math;
  var mr = m.round;
  var ms = m.sin;
  var mc = m.cos;
  var abs = m.abs;
  var sqrt = m.sqrt;

  // this is used for sub pixel precision
  var Z = 10;
  var Z2 = Z / 2;

  /**
	* This funtion is assigned to the <canvas> elements as element.getContext().
	* @this {HTMLElement}
	* @return {CanvasRenderingContext2D_}
	*/
  function getContext() {
	return this.context_ ||
		(this.context_ = new CanvasRenderingContext2D_(this));
  }

  var slice = Array.prototype.slice;

  /**
	* Binds a function to an object. The returned function will always use the
	* passed in {@code obj} as {@code this}.
	*
	* Example:
	*
	*	g = bind(f, obj, a, b)
	*	g(c, d) // will do f.call(obj, a, b, c, d)
	*
	* @param {Function} f The function to bind the object to
	* @param {Object} obj The object that should act as this when the function
	*	 is called
	* @param {*} var_args Rest arguments that will be used as the initial
	*	 arguments when the function is called
	* @return {Function} A new function that has bound this
	*/
  function bind(f, obj, var_args) {
	var a = slice.call(arguments, 2);
	return function() {
		return f.apply(obj, a.concat(slice.call(arguments)));
	};
  }

  function encodeHtmlAttribute(s) {
	return String(s).replace(/&/g, '&amp;').replace(/"/g, '&quot;');
  }

  function addNamespacesAndStylesheet(doc) {
	// create xmlns
	if (!doc.namespaces['g_vml_']) {
		doc.namespaces.add('g_vml_', 'urn:schemas-microsoft-com:vml',
						 '#default#VML');

	}
	if (!doc.namespaces['g_o_']) {
		doc.namespaces.add('g_o_', 'urn:schemas-microsoft-com:office:office',
						 '#default#VML');
	}

	// Setup default CSS.  Only add one style sheet per document
	if (!doc.styleSheets['ex_canvas_']) {
		var ss = doc.createStyleSheet();
		ss.owningElement.id = 'ex_canvas_';
		ss.cssText = 'canvas{display:inline-block;overflow:hidden;' +
			// default size is 300x150 in Gecko and Opera
			'text-align:left;width:300px;height:150px}';
	}
  }

  // Add namespaces and stylesheet at startup.
  addNamespacesAndStylesheet(document);

  var G_vmlCanvasManager_ = {
	init: function(opt_doc) {
		if (/MSIE/.test(navigator.userAgent) && !window.opera) {
		var doc = opt_doc || document;
		// Create a dummy element so that IE will allow canvas elements to be
		// recognized.
		doc.createElement('canvas');
		doc.attachEvent('onreadystatechange', bind(this.init_, this, doc));
		}
	},

	init_: function(doc) {
		// find all canvas elements
		var els = doc.getElementsByTagName('canvas');
		for (var i = 0; i < els.length; i++) {
		this.initElement(els[i]);
		}
	},

	/**
	 * Public initializes a canvas element so that it can be used as canvas
	 * element from now on. This is called automatically before the page is
	 * loaded but if you are creating elements using createElement you need to
	 * make sure this is called on the element.
	 * @param {HTMLElement} el The canvas element to initialize.
	 * @return {HTMLElement} the element that was created.
	 */
	initElement: function(el) {
		if (!el.getContext) {
		el.getContext = getContext;

		// Add namespaces and stylesheet to document of the element.
		addNamespacesAndStylesheet(el.ownerDocument);

		// Remove fallback content. There is no way to hide text nodes so we
		// just remove all childNodes. We could hide all elements and remove
		// text nodes but who really cares about the fallback content.
		el.innerHTML = '';

		// do not use inline function because that will leak memory
		el.attachEvent('onpropertychange', onPropertyChange);
		el.attachEvent('onresize', onResize);

		var attrs = el.attributes;
		if (attrs.width && attrs.width.specified) {
			// TODO: use runtimeStyle and coordsize
			// el.getContext().setWidth_(attrs.width.nodeValue);
			el.style.width = attrs.width.nodeValue + 'px';
		} else {
			el.width = el.clientWidth;
		}
		if (attrs.height && attrs.height.specified) {
			// TODO: use runtimeStyle and coordsize
			// el.getContext().setHeight_(attrs.height.nodeValue);
			el.style.height = attrs.height.nodeValue + 'px';
		} else {
			el.height = el.clientHeight;
		}
		//el.getContext().setCoordsize_()
		}
		return el;
	}
  };

  function onPropertyChange(e) {
	var el = e.srcElement;

	switch (e.propertyName) {
		case 'width':
		el.getContext().clearRect();
		el.style.width = el.attributes.width.nodeValue + 'px';
		// In IE8 this does not trigger onresize.
		el.firstChild.style.width =  el.clientWidth + 'px';
		break;
		case 'height':
		el.getContext().clearRect();
		el.style.height = el.attributes.height.nodeValue + 'px';
		el.firstChild.style.height = el.clientHeight + 'px';
		break;
	}
  }

  function onResize(e) {
	var el = e.srcElement;
	if (el.firstChild) {
		el.firstChild.style.width =  el.clientWidth + 'px';
		el.firstChild.style.height = el.clientHeight + 'px';
	}
  }

  G_vmlCanvasManager_.init();

  // precompute "00" to "FF"
  var decToHex = [];
  for (var i = 0; i < 16; i++) {
	for (var j = 0; j < 16; j++) {
		decToHex[i * 16 + j] = i.toString(16) + j.toString(16);
	}
  }

  function createMatrixIdentity() {
	return [
		[1, 0, 0],
		[0, 1, 0],
		[0, 0, 1]
	];
  }

  function matrixMultiply(m1, m2) {
	var result = createMatrixIdentity();

	for (var x = 0; x < 3; x++) {
		for (var y = 0; y < 3; y++) {
		var sum = 0;

		for (var z = 0; z < 3; z++) {
			sum += m1[x][z] * m2[z][y];
		}

		result[x][y] = sum;
		}
	}
	return result;
  }

  function copyState(o1, o2) {
	o2.fillStyle	 = o1.fillStyle;
	o2.lineCap		= o1.lineCap;
	o2.lineJoin		= o1.lineJoin;
	o2.lineWidth	 = o1.lineWidth;
	o2.miterLimit	= o1.miterLimit;
	o2.shadowBlur	= o1.shadowBlur;
	o2.shadowColor	= o1.shadowColor;
	o2.shadowOffsetX = o1.shadowOffsetX;
	o2.shadowOffsetY = o1.shadowOffsetY;
	o2.strokeStyle	= o1.strokeStyle;
	o2.globalAlpha	= o1.globalAlpha;
	o2.font			= o1.font;
	o2.textAlign	 = o1.textAlign;
	o2.textBaseline  = o1.textBaseline;
	o2.arcScaleX_	= o1.arcScaleX_;
	o2.arcScaleY_	= o1.arcScaleY_;
	o2.lineScale_	= o1.lineScale_;
  }

  var colorData = {
	aliceblue: '#F0F8FF',
	antiquewhite: '#FAEBD7',
	aquamarine: '#7FFFD4',
	azure: '#F0FFFF',
	beige: '#F5F5DC',
	bisque: '#FFE4C4',
	black: '#000000',
	blanchedalmond: '#FFEBCD',
	blueviolet: '#8A2BE2',
	brown: '#A52A2A',
	burlywood: '#DEB887',
	cadetblue: '#5F9EA0',
	chartreuse: '#7FFF00',
	chocolate: '#D2691E',
	coral: '#FF7F50',
	cornflowerblue: '#6495ED',
	cornsilk: '#FFF8DC',
	crimson: '#DC143C',
	cyan: '#00FFFF',
	darkblue: '#00008B',
	darkcyan: '#008B8B',
	darkgoldenrod: '#B8860B',
	darkgray: '#A9A9A9',
	darkgreen: '#006400',
	darkgrey: '#A9A9A9',
	darkkhaki: '#BDB76B',
	darkmagenta: '#8B008B',
	darkolivegreen: '#556B2F',
	darkorange: '#FF8C00',
	darkorchid: '#9932CC',
	darkred: '#8B0000',
	darksalmon: '#E9967A',
	darkseagreen: '#8FBC8F',
	darkslateblue: '#483D8B',
	darkslategray: '#2F4F4F',
	darkslategrey: '#2F4F4F',
	darkturquoise: '#00CED1',
	darkviolet: '#9400D3',
	deeppink: '#FF1493',
	deepskyblue: '#00BFFF',
	dimgray: '#696969',
	dimgrey: '#696969',
	dodgerblue: '#1E90FF',
	firebrick: '#B22222',
	floralwhite: '#FFFAF0',
	forestgreen: '#228B22',
	gainsboro: '#DCDCDC',
	ghostwhite: '#F8F8FF',
	gold: '#FFD700',
	goldenrod: '#DAA520',
	grey: '#808080',
	greenyellow: '#ADFF2F',
	honeydew: '#F0FFF0',
	hotpink: '#FF69B4',
	indianred: '#CD5C5C',
	indigo: '#4B0082',
	ivory: '#FFFFF0',
	khaki: '#F0E68C',
	lavender: '#E6E6FA',
	lavenderblush: '#FFF0F5',
	lawngreen: '#7CFC00',
	lemonchiffon: '#FFFACD',
	lightblue: '#ADD8E6',
	lightcoral: '#F08080',
	lightcyan: '#E0FFFF',
	lightgoldenrodyellow: '#FAFAD2',
	lightgreen: '#90EE90',
	lightgrey: '#D3D3D3',
	lightpink: '#FFB6C1',
	lightsalmon: '#FFA07A',
	lightseagreen: '#20B2AA',
	lightskyblue: '#87CEFA',
	lightslategray: '#778899',
	lightslategrey: '#778899',
	lightsteelblue: '#B0C4DE',
	lightyellow: '#FFFFE0',
	limegreen: '#32CD32',
	linen: '#FAF0E6',
	magenta: '#FF00FF',
	mediumaquamarine: '#66CDAA',
	mediumblue: '#0000CD',
	mediumorchid: '#BA55D3',
	mediumpurple: '#9370DB',
	mediumseagreen: '#3CB371',
	mediumslateblue: '#7B68EE',
	mediumspringgreen: '#00FA9A',
	mediumturquoise: '#48D1CC',
	mediumvioletred: '#C71585',
	midnightblue: '#191970',
	mintcream: '#F5FFFA',
	mistyrose: '#FFE4E1',
	moccasin: '#FFE4B5',
	navajowhite: '#FFDEAD',
	oldlace: '#FDF5E6',
	olivedrab: '#6B8E23',
	orange: '#FFA500',
	orangered: '#FF4500',
	orchid: '#DA70D6',
	palegoldenrod: '#EEE8AA',
	palegreen: '#98FB98',
	paleturquoise: '#AFEEEE',
	palevioletred: '#DB7093',
	papayawhip: '#FFEFD5',
	peachpuff: '#FFDAB9',
	peru: '#CD853F',
	pink: '#FFC0CB',
	plum: '#DDA0DD',
	powderblue: '#B0E0E6',
	rosybrown: '#BC8F8F',
	royalblue: '#4169E1',
	saddlebrown: '#8B4513',
	salmon: '#FA8072',
	sandybrown: '#F4A460',
	seagreen: '#2E8B57',
	seashell: '#FFF5EE',
	sienna: '#A0522D',
	skyblue: '#87CEEB',
	slateblue: '#6A5ACD',
	slategray: '#708090',
	slategrey: '#708090',
	snow: '#FFFAFA',
	springgreen: '#00FF7F',
	steelblue: '#4682B4',
	tan: '#D2B48C',
	thistle: '#D8BFD8',
	tomato: '#FF6347',
	turquoise: '#40E0D0',
	violet: '#EE82EE',
	wheat: '#F5DEB3',
	whitesmoke: '#F5F5F5',
	yellowgreen: '#9ACD32'
  };


  function getRgbHslContent(styleString) {
	var start = styleString.indexOf('(', 3);
	var end = styleString.indexOf(')', start + 1);
	var parts = styleString.substring(start + 1, end).split(',');
	// add alpha if needed
	if (parts.length == 4 && styleString.substr(3, 1) == 'a') {
		alpha = Number(parts[3]);
	} else {
		parts[3] = 1;
	}
	return parts;
  }

  function percent(s) {
	return parseFloat(s) / 100;
  }

  function clamp(v, min, max) {
	return Math.min(max, Math.max(min, v));
  }

  function hslToRgb(parts){
	var r, g, b;
	h = parseFloat(parts[0]) / 360 % 360;
	if (h < 0)
		h++;
	s = clamp(percent(parts[1]), 0, 1);
	l = clamp(percent(parts[2]), 0, 1);
	if (s == 0) {
		r = g = b = l; // achromatic
	} else {
		var q = l < 0.5 ? l * (1 + s) : l + s - l * s;
		var p = 2 * l - q;
		r = hueToRgb(p, q, h + 1 / 3);
		g = hueToRgb(p, q, h);
		b = hueToRgb(p, q, h - 1 / 3);
	}

	return '#' + decToHex[Math.floor(r * 255)] +
		decToHex[Math.floor(g * 255)] +
		decToHex[Math.floor(b * 255)];
  }

  function hueToRgb(m1, m2, h) {
	if (h < 0)
		h++;
	if (h > 1)
		h--;

	if (6 * h < 1)
		return m1 + (m2 - m1) * 6 * h;
	else if (2 * h < 1)
		return m2;
	else if (3 * h < 2)
		return m1 + (m2 - m1) * (2 / 3 - h) * 6;
	else
		return m1;
  }

  function processStyle(styleString) {
	var str, alpha = 1;

	styleString = String(styleString);
	if (styleString.charAt(0) == '#') {
		str = styleString;
	} else if (/^rgb/.test(styleString)) {
		var parts = getRgbHslContent(styleString);
		var str = '#', n;
		for (var i = 0; i < 3; i++) {
		if (parts[i].indexOf('%') != -1) {
			n = Math.floor(percent(parts[i]) * 255);
		} else {
			n = Number(parts[i]);
		}
		str += decToHex[clamp(n, 0, 255)];
		}
		alpha = parts[3];
	} else if (/^hsl/.test(styleString)) {
		var parts = getRgbHslContent(styleString);
		str = hslToRgb(parts);
		alpha = parts[3];
	} else {
		str = colorData[styleString] || styleString;
	}
	return {color: str, alpha: alpha};
  }

  var DEFAULT_STYLE = {
	style: 'normal',
	variant: 'normal',
	weight: 'normal',
	size: 10,
	family: 'sans-serif'
  };

  // Internal text style cache
  var fontStyleCache = {};

  function processFontStyle(styleString) {
	if (fontStyleCache[styleString]) {
		return fontStyleCache[styleString];
	}

	var el = document.createElement('div');
	var style = el.style;
	try {
		style.font = styleString;
	} catch (ex) {
		// Ignore failures to set to invalid font.
	}

	return fontStyleCache[styleString] = {
		style: style.fontStyle || DEFAULT_STYLE.style,
		variant: style.fontVariant || DEFAULT_STYLE.variant,
		weight: style.fontWeight || DEFAULT_STYLE.weight,
		size: style.fontSize || DEFAULT_STYLE.size,
		family: style.fontFamily || DEFAULT_STYLE.family
	};
  }

  function getComputedStyle(style, element) {
	var computedStyle = {};

	for (var p in style) {
		computedStyle[p] = style[p];
	}

	// Compute the size
	var canvasFontSize = parseFloat(element.currentStyle.fontSize),
		fontSize = parseFloat(style.size);

	if (typeof style.size == 'number') {
		computedStyle.size = style.size;
	} else if (style.size.indexOf('px') != -1) {
		computedStyle.size = fontSize;
	} else if (style.size.indexOf('em') != -1) {
		computedStyle.size = canvasFontSize * fontSize;
	} else if(style.size.indexOf('%') != -1) {
		computedStyle.size = (canvasFontSize / 100) * fontSize;
	} else if (style.size.indexOf('pt') != -1) {
		computedStyle.size = fontSize / .75;
	} else {
		computedStyle.size = canvasFontSize;
	}

	// Different scaling between normal text and VML text. This was found using
	// trial and error to get the same size as non VML text.
	computedStyle.size *= 0.981;

	return computedStyle;
  }

  function buildStyle(style) {
	return style.style + ' ' + style.variant + ' ' + style.weight + ' ' +
		style.size + 'px ' + style.family;
  }

  function processLineCap(lineCap) {
	switch (lineCap) {
		case 'butt':
		return 'flat';
		case 'round':
		return 'round';
		case 'square':
		default:
		return 'square';
	}
  }

  /**
	* This class implements CanvasRenderingContext2D interface as described by
	* the WHATWG.
	* @param {HTMLElement} surfaceElement The element that the 2D context should
	* be associated with
	*/
  function CanvasRenderingContext2D_(surfaceElement) {
	this.m_ = createMatrixIdentity();

	this.mStack_ = [];
	this.aStack_ = [];
	this.currentPath_ = [];

	// Canvas context properties
	this.strokeStyle = '#000';
	this.fillStyle = '#000';

	this.lineWidth = 1;
	this.lineJoin = 'miter';
	this.lineCap = 'butt';
	this.miterLimit = Z * 1;
	this.globalAlpha = 1;
	this.font = '10px sans-serif';
	this.textAlign = 'left';
	this.textBaseline = 'alphabetic';
	this.canvas = surfaceElement;

	var el = surfaceElement.ownerDocument.createElement('div');
	el.style.width =  surfaceElement.clientWidth + 'px';
	el.style.height = surfaceElement.clientHeight + 'px';
	el.style.overflow = 'hidden';
	el.style.position = 'absolute';
	surfaceElement.appendChild(el);

	this.element_ = el;
	this.arcScaleX_ = 1;
	this.arcScaleY_ = 1;
	this.lineScale_ = 1;
  }

  var contextPrototype = CanvasRenderingContext2D_.prototype;
  contextPrototype.clearRect = function() {
	if (this.textMeasureEl_) {
		this.textMeasureEl_.removeNode(true);
		this.textMeasureEl_ = null;
	}
	this.element_.innerHTML = '';
  };

  contextPrototype.beginPath = function() {
	// TODO: Branch current matrix so that save/restore has no effect
	//		as per safari docs.
	this.currentPath_ = [];
  };

  contextPrototype.moveTo = function(aX, aY) {
	var p = this.getCoords_(aX, aY);
	this.currentPath_.push({type: 'moveTo', x: p.x, y: p.y});
	this.currentX_ = p.x;
	this.currentY_ = p.y;
  };

  contextPrototype.lineTo = function(aX, aY) {
	var p = this.getCoords_(aX, aY);
	this.currentPath_.push({type: 'lineTo', x: p.x, y: p.y});

	this.currentX_ = p.x;
	this.currentY_ = p.y;
  };

  contextPrototype.bezierCurveTo = function(aCP1x, aCP1y,
											aCP2x, aCP2y,
											aX, aY) {
	var p = this.getCoords_(aX, aY);
	var cp1 = this.getCoords_(aCP1x, aCP1y);
	var cp2 = this.getCoords_(aCP2x, aCP2y);
	bezierCurveTo(this, cp1, cp2, p);
  };

  // Helper function that takes the already fixed cordinates.
  function bezierCurveTo(self, cp1, cp2, p) {
	self.currentPath_.push({
		type: 'bezierCurveTo',
		cp1x: cp1.x,
		cp1y: cp1.y,
		cp2x: cp2.x,
		cp2y: cp2.y,
		x: p.x,
		y: p.y
	});
	self.currentX_ = p.x;
	self.currentY_ = p.y;
  }

  contextPrototype.quadraticCurveTo = function(aCPx, aCPy, aX, aY) {
	// the following is lifted almost directly from
	// http://developer.mozilla.org/en/docs/Canvas_tutorial:Drawing_shapes

	var cp = this.getCoords_(aCPx, aCPy);
	var p = this.getCoords_(aX, aY);

	var cp1 = {
		x: this.currentX_ + 2.0 / 3.0 * (cp.x - this.currentX_),
		y: this.currentY_ + 2.0 / 3.0 * (cp.y - this.currentY_)
	};
	var cp2 = {
		x: cp1.x + (p.x - this.currentX_) / 3.0,
		y: cp1.y + (p.y - this.currentY_) / 3.0
	};

	bezierCurveTo(this, cp1, cp2, p);
  };

  contextPrototype.arc = function(aX, aY, aRadius,
									aStartAngle, aEndAngle, aClockwise) {
	aRadius *= Z;
	var arcType = aClockwise ? 'at' : 'wa';

	var xStart = aX + mc(aStartAngle) * aRadius - Z2;
	var yStart = aY + ms(aStartAngle) * aRadius - Z2;

	var xEnd = aX + mc(aEndAngle) * aRadius - Z2;
	var yEnd = aY + ms(aEndAngle) * aRadius - Z2;

	// IE won't render arches drawn counter clockwise if xStart == xEnd.
	if (xStart == xEnd && !aClockwise) {
		xStart += 0.125; // Offset xStart by 1/80 of a pixel. Use something
						// that can be represented in binary
	}

	var p = this.getCoords_(aX, aY);
	var pStart = this.getCoords_(xStart, yStart);
	var pEnd = this.getCoords_(xEnd, yEnd);

	this.currentPath_.push({type: arcType,
							x: p.x,
							y: p.y,
							radius: aRadius,
							xStart: pStart.x,
							yStart: pStart.y,
							xEnd: pEnd.x,
							yEnd: pEnd.y});

  };

  contextPrototype.rect = function(aX, aY, aWidth, aHeight) {
	this.moveTo(aX, aY);
	this.lineTo(aX + aWidth, aY);
	this.lineTo(aX + aWidth, aY + aHeight);
	this.lineTo(aX, aY + aHeight);
	this.closePath();
  };

  contextPrototype.strokeRect = function(aX, aY, aWidth, aHeight) {
	var oldPath = this.currentPath_;
	this.beginPath();

	this.moveTo(aX, aY);
	this.lineTo(aX + aWidth, aY);
	this.lineTo(aX + aWidth, aY + aHeight);
	this.lineTo(aX, aY + aHeight);
	this.closePath();
	this.stroke();

	this.currentPath_ = oldPath;
  };

  contextPrototype.fillRect = function(aX, aY, aWidth, aHeight) {
	var oldPath = this.currentPath_;
	this.beginPath();

	this.moveTo(aX, aY);
	this.lineTo(aX + aWidth, aY);
	this.lineTo(aX + aWidth, aY + aHeight);
	this.lineTo(aX, aY + aHeight);
	this.closePath();
	this.fill();

	this.currentPath_ = oldPath;
  };

  contextPrototype.createLinearGradient = function(aX0, aY0, aX1, aY1) {
	var gradient = new CanvasGradient_('gradient');
	gradient.x0_ = aX0;
	gradient.y0_ = aY0;
	gradient.x1_ = aX1;
	gradient.y1_ = aY1;
	return gradient;
  };

  contextPrototype.createRadialGradient = function(aX0, aY0, aR0,
													aX1, aY1, aR1) {
	var gradient = new CanvasGradient_('gradientradial');
	gradient.x0_ = aX0;
	gradient.y0_ = aY0;
	gradient.r0_ = aR0;
	gradient.x1_ = aX1;
	gradient.y1_ = aY1;
	gradient.r1_ = aR1;
	return gradient;
  };

  contextPrototype.drawImage = function(image, var_args) {
	var dx, dy, dw, dh, sx, sy, sw, sh;

	// to find the original width we overide the width and height
	var oldRuntimeWidth = image.runtimeStyle.width;
	var oldRuntimeHeight = image.runtimeStyle.height;
	image.runtimeStyle.width = 'auto';
	image.runtimeStyle.height = 'auto';

	// get the original size
	var w = image.width;
	var h = image.height;

	// and remove overides
	image.runtimeStyle.width = oldRuntimeWidth;
	image.runtimeStyle.height = oldRuntimeHeight;

	if (arguments.length == 3) {
		dx = arguments[1];
		dy = arguments[2];
		sx = sy = 0;
		sw = dw = w;
		sh = dh = h;
	} else if (arguments.length == 5) {
		dx = arguments[1];
		dy = arguments[2];
		dw = arguments[3];
		dh = arguments[4];
		sx = sy = 0;
		sw = w;
		sh = h;
	} else if (arguments.length == 9) {
		sx = arguments[1];
		sy = arguments[2];
		sw = arguments[3];
		sh = arguments[4];
		dx = arguments[5];
		dy = arguments[6];
		dw = arguments[7];
		dh = arguments[8];
	} else {
		throw Error('Invalid number of arguments');
	}

	var d = this.getCoords_(dx, dy);

	var w2 = sw / 2;
	var h2 = sh / 2;

	var vmlStr = [];

	var W = 10;
	var H = 10;

	// For some reason that I've now forgotten, using divs didn't work
	vmlStr.push(' <g_vml_:group',
				' coordsize="', Z * W, ',', Z * H, '"',
				' coordorigin="0,0"' ,
				' style="width:', W, 'px;height:', H, 'px;position:absolute;');

	// If filters are necessary (rotation exists), create them
	// filters are bog-slow, so only create them if abbsolutely necessary
	// The following check doesn't account for skews (which don't exist
	// in the canvas spec (yet) anyway.

	if (this.m_[0][0] != 1 || this.m_[0][1] ||
		this.m_[1][1] != 1 || this.m_[1][0]) {
		var filter = [];

		// Note the 12/21 reversal
		filter.push('M11=', this.m_[0][0], ',',
					'M12=', this.m_[1][0], ',',
					'M21=', this.m_[0][1], ',',
					'M22=', this.m_[1][1], ',',
					'Dx=', mr(d.x / Z), ',',
					'Dy=', mr(d.y / Z), '');

		// Bounding box calculation (need to minimize displayed area so that
		// filters don't waste time on unused pixels.
		var max = d;
		var c2 = this.getCoords_(dx + dw, dy);
		var c3 = this.getCoords_(dx, dy + dh);
		var c4 = this.getCoords_(dx + dw, dy + dh);

		max.x = m.max(max.x, c2.x, c3.x, c4.x);
		max.y = m.max(max.y, c2.y, c3.y, c4.y);

		vmlStr.push('padding:0 ', mr(max.x / Z), 'px ', mr(max.y / Z),
					'px 0;filter:progid:DXImageTransform.Microsoft.Matrix(',
					filter.join(''), ", sizingmethod='clip');");

	} else {
		vmlStr.push('top:', mr(d.y / Z), 'px;left:', mr(d.x / Z), 'px;');
	}

	vmlStr.push(' ">' ,
				'<g_vml_:image src="', image.src, '"',
				' style="width:', Z * dw, 'px;',
				' height:', Z * dh, 'px"',
				' cropleft="', sx / w, '"',
				' croptop="', sy / h, '"',
				' cropright="', (w - sx - sw) / w, '"',
				' cropbottom="', (h - sy - sh) / h, '"',
				' />',
				'</g_vml_:group>');

	this.element_.insertAdjacentHTML('BeforeEnd', vmlStr.join(''));
  };

  contextPrototype.stroke = function(aFill) {
	var W = 10;
	var H = 10;
	// Divide the shape into chunks if it's too long because IE has a limit
	// somewhere for how long a VML shape can be. This simple division does
	// not work with fills, only strokes, unfortunately.
	var chunkSize = 5000;

	var min = {x: null, y: null};
	var max = {x: null, y: null};

	for (var j = 0; j < this.currentPath_.length; j += chunkSize) {
		var lineStr = [];
		var lineOpen = false;

		lineStr.push('<g_vml_:shape',
					' filled="', !!aFill, '"',
					' style="position:absolute;width:', W, 'px;height:', H, 'px;"',
					' coordorigin="0,0"',
					' coordsize="', Z * W, ',', Z * H, '"',
					' stroked="', !aFill, '"',
					' path="');

		var newSeq = false;

		for (var i = j; i < Math.min(j + chunkSize, this.currentPath_.length); i++) {
		if (i % chunkSize == 0 && i > 0) { // move into position for next chunk
			lineStr.push(' m ', mr(this.currentPath_[i-1].x), ',', mr(this.currentPath_[i-1].y));
		}

		var p = this.currentPath_[i];
		var c;

		switch (p.type) {
			case 'moveTo':
			c = p;
			lineStr.push(' m ', mr(p.x), ',', mr(p.y));
			break;
			case 'lineTo':
			lineStr.push(' l ', mr(p.x), ',', mr(p.y));
			break;
			case 'close':
			lineStr.push(' x ');
			p = null;
			break;
			case 'bezierCurveTo':
			lineStr.push(' c ',
						 mr(p.cp1x), ',', mr(p.cp1y), ',',
						 mr(p.cp2x), ',', mr(p.cp2y), ',',
						 mr(p.x), ',', mr(p.y));
			break;
			case 'at':
			case 'wa':
			lineStr.push(' ', p.type, ' ',
						 mr(p.x - this.arcScaleX_ * p.radius), ',',
						 mr(p.y - this.arcScaleY_ * p.radius), ' ',
						 mr(p.x + this.arcScaleX_ * p.radius), ',',
						 mr(p.y + this.arcScaleY_ * p.radius), ' ',
						 mr(p.xStart), ',', mr(p.yStart), ' ',
						 mr(p.xEnd), ',', mr(p.yEnd));
			break;
		}
		// TODO: Following is broken for curves due to
		//		move to proper paths.
		// Figure out dimensions so we can do gradient fills
		// properly
		if (p) {
			if (min.x == null || p.x < min.x) {
			min.x = p.x;
			}
			if (max.x == null || p.x > max.x) {
			max.x = p.x;
			}
			if (min.y == null || p.y < min.y) {
			min.y = p.y;
			}
			if (max.y == null || p.y > max.y) {
			max.y = p.y;
			}
		}
		}
		lineStr.push(' ">');
		if (!aFill) {
		appendStroke(this, lineStr);
		} else {
		appendFill(this, lineStr, min, max);
		}
		lineStr.push('</g_vml_:shape>');
		this.element_.insertAdjacentHTML('beforeEnd', lineStr.join(''));
	}
  };

  function appendStroke(ctx, lineStr) {
	var a = processStyle(ctx.strokeStyle);
	var color = a.color;
	var opacity = a.alpha * ctx.globalAlpha;
	var lineWidth = ctx.lineScale_ * ctx.lineWidth;

	// VML cannot correctly render a line if the width is less than 1px.
	// In that case, we dilute the color to make the line look thinner.
	if (lineWidth < 1) {
		opacity *= lineWidth;
	}

	lineStr.push(
		'<g_vml_:stroke',
		' opacity="', opacity, '"',
		' joinstyle="', ctx.lineJoin, '"',
		' miterlimit="', ctx.miterLimit, '"',
		' endcap="', processLineCap(ctx.lineCap), '"',
		' weight="', lineWidth, 'px"',
		' color="', color, '" />'
	);
  }

  function appendFill(ctx, lineStr, min, max) {
	var fillStyle = ctx.fillStyle;
	var arcScaleX = ctx.arcScaleX_;
	var arcScaleY = ctx.arcScaleY_;
	var width = max.x - min.x;
	var height = max.y - min.y;
	if (fillStyle instanceof CanvasGradient_) {
		// TODO: Gradients transformed with the transformation matrix.
		var angle = 0;
		var focus = {x: 0, y: 0};

		// additional offset
		var shift = 0;
		// scale factor for offset
		var expansion = 1;

		if (fillStyle.type_ == 'gradient') {
		var x0 = fillStyle.x0_ / arcScaleX;
		var y0 = fillStyle.y0_ / arcScaleY;
		var x1 = fillStyle.x1_ / arcScaleX;
		var y1 = fillStyle.y1_ / arcScaleY;
		var p0 = ctx.getCoords_(x0, y0);
		var p1 = ctx.getCoords_(x1, y1);
		var dx = p1.x - p0.x;
		var dy = p1.y - p0.y;
		angle = Math.atan2(dx, dy) * 180 / Math.PI;

		// The angle should be a non-negative number.
		if (angle < 0) {
			angle += 360;
		}

		// Very small angles produce an unexpected result because they are
		// converted to a scientific notation string.
		if (angle < 1e-6) {
			angle = 0;
		}
		} else {
		var p0 = ctx.getCoords_(fillStyle.x0_, fillStyle.y0_);
		focus = {
			x: (p0.x - min.x) / width,
			y: (p0.y - min.y) / height
		};

		width  /= arcScaleX * Z;
		height /= arcScaleY * Z;
		var dimension = m.max(width, height);
		shift = 2 * fillStyle.r0_ / dimension;
		expansion = 2 * fillStyle.r1_ / dimension - shift;
		}

		// We need to sort the color stops in ascending order by offset,
		// otherwise IE won't interpret it correctly.
		var stops = fillStyle.colors_;
		stops.sort(function(cs1, cs2) {
		return cs1.offset - cs2.offset;
		});

		var length = stops.length;
		var color1 = stops[0].color;
		var color2 = stops[length - 1].color;
		var opacity1 = stops[0].alpha * ctx.globalAlpha;
		var opacity2 = stops[length - 1].alpha * ctx.globalAlpha;

		var colors = [];
		for (var i = 0; i < length; i++) {
		var stop = stops[i];
		colors.push(stop.offset * expansion + shift + ' ' + stop.color);
		}

		// When colors attribute is used, the meanings of opacity and o:opacity2
		// are reversed.
		lineStr.push('<g_vml_:fill type="', fillStyle.type_, '"',
					' method="none" focus="100%"',
					' color="', color1, '"',
					' color2="', color2, '"',
					' colors="', colors.join(','), '"',
					' opacity="', opacity2, '"',
					' g_o_:opacity2="', opacity1, '"',
					' angle="', angle, '"',
					' focusposition="', focus.x, ',', focus.y, '" />');
	} else if (fillStyle instanceof CanvasPattern_) {
		if (width && height) {
		var deltaLeft = -min.x;
		var deltaTop = -min.y;
		lineStr.push('<g_vml_:fill',
					 ' position="',
					 deltaLeft / width * arcScaleX * arcScaleX, ',',
					 deltaTop / height * arcScaleY * arcScaleY, '"',
					 ' type="tile"',
					 // TODO: Figure out the correct size to fit the scale.
					 //' size="', w, 'px ', h, 'px"',
					 ' src="', fillStyle.src_, '" />');
		}
	} else {
		var a = processStyle(ctx.fillStyle);
		var color = a.color;
		var opacity = a.alpha * ctx.globalAlpha;
		lineStr.push('<g_vml_:fill color="', color, '" opacity="', opacity,
					'" />');
	}
  }

  contextPrototype.fill = function() {
	this.stroke(true);
  };

  contextPrototype.closePath = function() {
	this.currentPath_.push({type: 'close'});
  };

  /**
	* @private
	*/
  contextPrototype.getCoords_ = function(aX, aY) {
	var m = this.m_;
	return {
		x: Z * (aX * m[0][0] + aY * m[1][0] + m[2][0]) - Z2,
		y: Z * (aX * m[0][1] + aY * m[1][1] + m[2][1]) - Z2
	};
  };

  contextPrototype.save = function() {
	var o = {};
	copyState(this, o);
	this.aStack_.push(o);
	this.mStack_.push(this.m_);
	this.m_ = matrixMultiply(createMatrixIdentity(), this.m_);
  };

  contextPrototype.restore = function() {
	if (this.aStack_.length) {
		copyState(this.aStack_.pop(), this);
		this.m_ = this.mStack_.pop();
	}
  };

  function matrixIsFinite(m) {
	return isFinite(m[0][0]) && isFinite(m[0][1]) &&
		isFinite(m[1][0]) && isFinite(m[1][1]) &&
		isFinite(m[2][0]) && isFinite(m[2][1]);
  }

  function setM(ctx, m, updateLineScale) {
	if (!matrixIsFinite(m)) {
		return;
	}
	ctx.m_ = m;

	if (updateLineScale) {
		// Get the line scale.
		// Determinant of this.m_ means how much the area is enlarged by the
		// transformation. So its square root can be used as a scale factor
		// for width.
		var det = m[0][0] * m[1][1] - m[0][1] * m[1][0];
		ctx.lineScale_ = sqrt(abs(det));
	}
  }

  contextPrototype.translate = function(aX, aY) {
	var m1 = [
		[1,  0,  0],
		[0,  1,  0],
		[aX, aY, 1]
	];

	setM(this, matrixMultiply(m1, this.m_), false);
  };

  contextPrototype.rotate = function(aRot) {
	var c = mc(aRot);
	var s = ms(aRot);

	var m1 = [
		[c,  s, 0],
		[-s, c, 0],
		[0,  0, 1]
	];

	setM(this, matrixMultiply(m1, this.m_), false);
  };

  contextPrototype.scale = function(aX, aY) {
	this.arcScaleX_ *= aX;
	this.arcScaleY_ *= aY;
	var m1 = [
		[aX, 0,  0],
		[0,  aY, 0],
		[0,  0,  1]
	];

	setM(this, matrixMultiply(m1, this.m_), true);
  };

  contextPrototype.transform = function(m11, m12, m21, m22, dx, dy) {
	var m1 = [
		[m11, m12, 0],
		[m21, m22, 0],
		[dx,  dy,  1]
	];

	setM(this, matrixMultiply(m1, this.m_), true);
  };

  contextPrototype.setTransform = function(m11, m12, m21, m22, dx, dy) {
	var m = [
		[m11, m12, 0],
		[m21, m22, 0],
		[dx,  dy,  1]
	];

	setM(this, m, true);
  };

  /**
	* The text drawing function.
	* The maxWidth argument isn't taken in account, since no browser supports
	* it yet.
	*/
  contextPrototype.drawText_ = function(text, x, y, maxWidth, stroke) {
	var m = this.m_,
		delta = 1000,
		left = 0,
		right = delta,
		offset = {x: 0, y: 0},
		lineStr = [];

	var fontStyle = getComputedStyle(processFontStyle(this.font),
									 this.element_);

	var fontStyleString = buildStyle(fontStyle);

	var elementStyle = this.element_.currentStyle;
	var textAlign = this.textAlign.toLowerCase();
	switch (textAlign) {
		case 'left':
		case 'center':
		case 'right':
		break;
		case 'end':
		textAlign = elementStyle.direction == 'ltr' ? 'right' : 'left';
		break;
		case 'start':
		textAlign = elementStyle.direction == 'rtl' ? 'right' : 'left';
		break;
		default:
		textAlign = 'left';
	}

	// 1.75 is an arbitrary number, as there is no info about the text baseline
	switch (this.textBaseline) {
		case 'hanging':
		case 'top':
		offset.y = fontStyle.size / 1.75;
		break;
		case 'middle':
		break;
		default:
		case null:
		case 'alphabetic':
		case 'ideographic':
		case 'bottom':
		offset.y = -fontStyle.size / 2.25;
		break;
	}

	switch(textAlign) {
		case 'right':
		left = delta;
		right = 0.05;
		break;
		case 'center':
		left = right = delta / 2;
		break;
	}

	var d = this.getCoords_(x + offset.x, y + offset.y);

	lineStr.push('<g_vml_:line from="', -left ,' 0" to="', right ,' 0.05" ',
				 ' coordsize="100 100" coordorigin="0 0"',
				 ' filled="', !stroke, '" stroked="', !!stroke,
				 '" style="position:absolute;width:1px;height:1px;">');

	if (stroke) {
		appendStroke(this, lineStr);
	} else {
		// TODO: Fix the min and max params.
		appendFill(this, lineStr, {x: -left, y: 0},
				 {x: right, y: fontStyle.size});
	}

	var skewM = m[0][0].toFixed(3) + ',' + m[1][0].toFixed(3) + ',' +
				m[0][1].toFixed(3) + ',' + m[1][1].toFixed(3) + ',0,0';

	var skewOffset = mr(d.x / Z) + ',' + mr(d.y / Z);

	lineStr.push('<g_vml_:skew on="t" matrix="', skewM ,'" ',
				 ' offset="', skewOffset, '" origin="', left ,' 0" />',
				 '<g_vml_:path textpathok="true" />',
				 '<g_vml_:textpath on="true" string="',
				 encodeHtmlAttribute(text),
				 '" style="v-text-align:', textAlign,
				 ';font:', encodeHtmlAttribute(fontStyleString),
				 '" /></g_vml_:line>');

	this.element_.insertAdjacentHTML('beforeEnd', lineStr.join(''));
  };

  contextPrototype.fillText = function(text, x, y, maxWidth) {
	this.drawText_(text, x, y, maxWidth, false);
  };

  contextPrototype.strokeText = function(text, x, y, maxWidth) {
	this.drawText_(text, x, y, maxWidth, true);
  };

  contextPrototype.measureText = function(text) {
	if (!this.textMeasureEl_) {
		var s = '<span style="position:absolute;' +
			'top:-20000px;left:0;padding:0;margin:0;border:none;' +
			'white-space:pre;"></span>';
		this.element_.insertAdjacentHTML('beforeEnd', s);
		this.textMeasureEl_ = this.element_.lastChild;
	}
	var doc = this.element_.ownerDocument;
	this.textMeasureEl_.innerHTML = '';
	this.textMeasureEl_.style.font = this.font;
	// Don't use innerHTML or innerText because they allow markup/whitespace.
	this.textMeasureEl_.appendChild(doc.createTextNode(text));
	return {width: this.textMeasureEl_.offsetWidth};
  };

  /******** STUBS ********/
  contextPrototype.clip = function() {
	// TODO: Implement
  };

  contextPrototype.arcTo = function() {
	// TODO: Implement
  };

  contextPrototype.createPattern = function(image, repetition) {
	return new CanvasPattern_(image, repetition);
  };

  // Gradient / Pattern Stubs
  function CanvasGradient_(aType) {
	this.type_ = aType;
	this.x0_ = 0;
	this.y0_ = 0;
	this.r0_ = 0;
	this.x1_ = 0;
	this.y1_ = 0;
	this.r1_ = 0;
	this.colors_ = [];
  }

  CanvasGradient_.prototype.addColorStop = function(aOffset, aColor) {
	aColor = processStyle(aColor);
	this.colors_.push({offset: aOffset,
						color: aColor.color,
						alpha: aColor.alpha});
  };

  function CanvasPattern_(image, repetition) {
	assertImageIsValid(image);
	switch (repetition) {
		case 'repeat':
		case null:
		case '':
		this.repetition_ = 'repeat';
		break
		case 'repeat-x':
		case 'repeat-y':
		case 'no-repeat':
		this.repetition_ = repetition;
		break;
		default:
		throwException('SYNTAX_ERR');
	}

	this.src_ = image.src;
	this.width_ = image.width;
	this.height_ = image.height;
  }

  function throwException(s) {
	throw new DOMException_(s);
  }

  function assertImageIsValid(img) {
	if (!img || img.nodeType != 1 || img.tagName != 'IMG') {
		throwException('TYPE_MISMATCH_ERR');
	}
	if (img.readyState != 'complete') {
		throwException('INVALID_STATE_ERR');
	}
  }

  function DOMException_(s) {
	this.code = this[s];
	this.message = s +': DOM Exception ' + this.code;
  }
  var p = DOMException_.prototype = new Error;
  p.INDEX_SIZE_ERR = 1;
  p.DOMSTRING_SIZE_ERR = 2;
  p.HIERARCHY_REQUEST_ERR = 3;
  p.WRONG_DOCUMENT_ERR = 4;
  p.INVALID_CHARACTER_ERR = 5;
  p.NO_DATA_ALLOWED_ERR = 6;
  p.NO_MODIFICATION_ALLOWED_ERR = 7;
  p.NOT_FOUND_ERR = 8;
  p.NOT_SUPPORTED_ERR = 9;
  p.INUSE_ATTRIBUTE_ERR = 10;
  p.INVALID_STATE_ERR = 11;
  p.SYNTAX_ERR = 12;
  p.INVALID_MODIFICATION_ERR = 13;
  p.NAMESPACE_ERR = 14;
  p.INVALID_ACCESS_ERR = 15;
  p.VALIDATION_ERR = 16;
  p.TYPE_MISMATCH_ERR = 17;

  // set up externs
  G_vmlCanvasManager = G_vmlCanvasManager_;
  CanvasRenderingContext2D = CanvasRenderingContext2D_;
  CanvasGradient = CanvasGradient_;
  CanvasPattern = CanvasPattern_;
  DOMException = DOMException_;
})();

} // if
